What is the minimum depth of tread for existing exit stairs?

The minimum depth of tread for existing exit stairs is typically established to ensure safety and accessibility for individuals using the stairs. A depth of 230 mm, which is the correct answer, provides a sufficient amount of surface area for foot placement, reducing the risk of slipping and enhancing overall stability when navigating stairs. This dimension is widely considered standard in building codes and regulations for stair design, acknowledging the need for a balance between safety and comfortable usage.

Tread depths below this standard may not provide adequate support for users, which could lead to accidents or discomfort, while greater depths could lead to unnecessary bulkiness of stairs that inhibit space efficiency and design considerations. In the context of existing structures, maintaining the consistency of tread depth with recognized standards is crucial for ensuring compliance and user safety.